Mechanically interlocked pulsing dial selector switch



March 29, 1949. E L ET AL 2,465,397

MECHANICALLY KED PULSING INTERLOC DIAL SELECTOR SWITCH Filed Oct. 27, 1947 5 A MANUALCRELEASE awuc/nfow EDWIN L. POW L ALBERT E.SHOWA R atta- Patented Mar. 29, 1949 MECHANICALLY INTERLOCKED PULSING DIAL SELECTOR SWITCH Edwin L. Powell and Albert E. Showalter, Washington, D. C.

Application October 27, 1947, Serial No. 782,242

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 3 Claims.

This invention relates generally to electrical switching devices and particularly to an interlocking circuit-activating switch useful in dialoperated electrical control systems and the like.

In numerous electrical systems such as telephone or radio communication systems employing plurality of independent circuits having associated channels, it is frequently desirable to provide a central or unitary control system from which a single operator may select channels associated with any one or all of the independent circuits, as desired. In general, most of such unitary control systems employ mechanical dialoperated pulse-generating devices in each independent circuit, whereby the electrical impulses produced by such devices operate to actuate stepper relays or the like, also incorporated in the independent circuits, for selecting the desired communication channels. In numerous applications of such control systems, it would be convenient and desirable to incorporate an interlocking circuit-activating switch whereby any one of the independent circuits may be selectively actuated by a single pulse-generating device; and then, after operation of the pulse-generating device, to have the circuit-activating switch automatically return to an off position wherein further operation of the pulse-generating device is impotent to actuate any of the independent circuits until the circuit-activating switch is first manually reset by the operator.

It is therefore an object of the present invention to provide a novel control system having the foregoing advantages and features.

It is another object of the present invention to provide a novel inter-locking circuit-activating switch having the above features and which is useful in connection with either single or mul tiple dial-operated control systems and the like to prevent unintentional interruption of any active channel as a result of unauthorized and/or unpremeditated manipulation of the dial-operated channel selector.

Other objects and features of the present invention will becomeapparent from the following detailed description when read in conjunction with the accompanying drawings, in which Fig. l is a rear elevational view of one embodiment of the invention, and Figs. 2 and 3 are respectively side and front elevational views of the embodiment illustrated in Fig. 1.

In detail, the pulse-generating device is exemplified in the drawings as a standard springloaded telephone dial mechanism I, with integral rotatable dial, rotating shaft Ill, helical re 2 storing spring II, and pulse-generating mechanism (not shown); operable to permit by manual control selective generation of from one to say ten impulses for each dialing operation. The dial and pulse generating mechanism i is mounted as by screws 22, 23 and 24 on a suitable base plate 26. The rotating shaft l0, helical restoring spring H and pulse-generating mechanism are projected from the back of the dialing mechanism i through an opening 25 in the base plate 26. Attached to, by locking screw l2, and rotatable with shaft in is a claw-shaped cam 2. Cam 2 is arranged to engage and actuate an elongated pawl 8, which serves to provide a locking and escapement mechanism for a spring loaded circuit-activating switch indicated in general at 3. In particular, at the end of each dialing operation cam 2 actuates pawl 8 in a manner presently to be described to permit switch 3 to automatically reset to an off position under the urging of a helical reset spring i2 positioned about the switch shaft 34.

Pawl 8 is slidably mounted at each end as by guide screws and 16 on support 9 and stud 18. Guide screw l5, positioned at the end of the pawl adjacent the circuit-activating switch 3, passes through an elongated opening 20 designed to permit longitudinal and pivotal movements of the pawl, whereas opening formed in the opposite end of the pawl and through which guide screw l6 passes is enlarged in all respects to thereby permit both longitudinal and lateral movements of this end of the pawl. For reasons soon to leecome apparent pawl 8 is urged toward the switch 3 by a helical tension spring l4 anchored at one end 29 in the pawl and at the other end 30 to stud 3 I, mounted on base plate 26.

As illustrated in the drawings and in particular in Fig. 1, circuit-activating switch 3 may in general be of standard construction suitably mounted on base plate 26 above the dialing mechanism i, and comprises a rotatable contactor 32 to which the electrical output from the dialing mechanism is fed as by electrical conductor 2'! and a plurality of fixed contacts 33 to which the several circuits to be energized by the dialing mechanism may be selectively connected. In particular, rotatable contactor 32 is rigidiy attached in suitable manner to rotatable shaft 34 and manually adjusted by knob 35. Mounted, on insulating placque 28, in circular relation about contactor 32 and adapted to be selectively contacted thereby on manual operation of knob 35 are the fixed contacts which are at least equal in numher to the number of independent circuits to be 3 selectively energized. Also rigidly attached to the rotatable shaft 34 of the circuit-activating switch 3 and rotatable therewith is a metal ratchet wheel I3 formed with a series of serrated notches cut in the periphery thereof for engagement with the pawl member 8.

These notches are so formed as to freely permit counter clockwise movement (Fig. 1) of the switch 3, but to then engage with the pawl 8 to prevent clockwise movement of the switch except at the end of a dialing operation (or when manually released in a manner presently to be described). Wound around the shaft 34 of the switch 3 is an adjustable helical restoring spring I2 anchored at one end in the switch end plate I? and at its opposite end in ratchet wheel I3, as by pilot holes 35, Spring I2 is wound in such a manner that upon clockwise movement of the switch 3 (Fig. 3), the spring becomes loaded and will tend to force the switch in a maximum counterclockwise direction (Fig. 3) to the off position, but is prevented from doing so by the engag ment between the ratchet I 3 and pawl 3.

In operation, circuit-activating switch 3 is first turned clockwise..(Fig. 3) to activate the desired circuit to be dialled. Thereafter, the dial mechanism I is rotated clockwise, from the desired channel position to the finger stop, and then released for the generation of the number of impulses required to select the desired channel. In initially rotating the dial mechanism I, cam 2 as seen in Fig. 1 moves counter-clockwise, passing over the shoulder I9 of pawl 8, and as it does 50 causing pawl 8 to move laterally at guide screw I6 without disengaging the pawl from the ratchet I3. Then, when the dial mechanism I reverses direction of rotation by virtue of its return spring I I, cam 2 engages shoulder I9 of the pawl (after generation of the final pulse) and causes the same to move downward and out of the notches on ratchet wheel I3, permitting the loadin spring I2 to return switch 3 to the off position, and disconnecting the circuit which has been controlled.

Manual release button is added for the convenience of the operation inasmuch as the switch 3 (in the event of having been set incorrectly) cannot be turned in a counter-clockwise direc tion as viewed from the front. However, manual depression of said button activates L-shaped lever 6, which is pivoted at its knee on pivot screw 4, and pushes downward against a shoulder 31, made a part of the pawl 8, thereby pushing pawl 8 away from the notches in the ratchet wheel I3 and releasing selector switch 3 to return to off position, whereupon it may be reset to the correct circuit to be controlled. Spring 1, consisting of a phosphor bronze or similar pressure loop, is anchored to the support 9 by screw and serves to return the L-shaped lever 6 to its original position on release of button 5.

Although we have shown and described only a limited and specific embodiment of the present invention it must be understood that we are fully aware of the many modifications possible thereof.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. In combination, a mechanically operated pulse generating device having a rotatable shaft, a multi-position selector switch having a rotatable contactor and a plurality of fixed contacts includ- Lin an ofi position from which different circuits maybe actuated, means for urging said contactor to the off position means connectin the output of said pulse generating device to said rotatable contactor, a locking mechanism engaging the contactor of said selector switch for holding the same in any selectable position, and a release arm carried by the rotatable shaft of said pulse generating device operative to disengage the locking mechanism at the end of a pulse generating cycle thereby permitting the contactor to return to the off position.

2. In combination with a dial-operated pulse generating device havin a rotatable shaft, a multi-position selector switch comprising a rotatable contactor and a plurality of fixed contacts including an off position, a ratchet mechanism carried by said contactor and movable therewith, a loading spring for urging said contactor to the ofi position, a pawl member engaging said ratchet mechanism and holding said contactor in a selectable position, and means operated from the rotatable shaft of said dialing mechanism for actuating said pawl member at the end of a dialing cycle to withdraw the pawl from the ratchet and permit the loading spring to return the selector switch to the off position.

3.. In combination with a dial-operated pulse generating device having a rotatable shaft, 9. multi-position selector switch comprising a rotatable contactor and a plurality of fixed contacts including an off position from which independent circuits may be selectably actuated, means connecting the output from said pulse generating device to said rotatable contactor, a loading spring operative to urge said rotatable contactor to said off position, a stop mechanism for retaining said rotatable contactor in a given setting against the action of said loading spring, and means operable from the rotating shaft of said dialing mechanism for disengaging said stop mechanism at the end of a dialing cycle, thereby to permit said loading spring to return said contactor to the off position.

EDWIN L. POWELL. ALBERT E. SHOWALTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name .Date

1,356,626 Hullt Oct. 26, 1920 1,963,600 Voss June 19, 1934 2,345,136 Lomax Mar. 28, 1944 2,416,463 Winkler Feb. 25, "1947 

